Abies durangensis var. durangensis

Pinaceae Abies durangensis var. durangensis Martínez

Etymology
Abies refers to ‘to rise’; indicating large trees.
durangensis refers to the Mexican state Durango.

Colloquial Name
Durango fir

Description
These trees grow between 30 and 40 meters tall, with a straight, column-like trunk that remains unbranched in the lower half. The crown is either narrowly pyramidal or more rounded in shape. The bark is smooth and greyish or reddish-brown when young but darkens to a nearly black shade with deep fissures at the base as the tree ages.

The main branches are long and spread out horizontally, while the smaller secondary branches either spread outward or angle slightly upward. The twigs are firm, slender, and have a dark purplish-red or reddish-brown color, later turning brown as they mature. Their surface is prominently ridged and grooved between the needle attachments and may be smooth or have fine hairs in the grooves. The scars left by fallen needles are rounded or slightly oval.

The buds are small, oblong, and about 4 to 5 mm long. They are covered in sticky resin, which gives them a dark brown appearance under a yellowish layer of dried resin. These bud scales stay on the tree for two to three years before falling off. The needles are arranged in a spiral pattern along the twigs, with most spreading outward in a comb-like pattern. They may curve slightly forward or backward, and on cone-bearing branches, they either spread similarly or angle weakly upward. They range from 2 to 3.5 cm long, sometimes reaching 4.5 cm. The base of each needle is slightly twisted, and the shape is long and narrow, tapering to a pointed or slightly rounded tip. Their color varies from dark green to light green. The lower surface has two distinct bands of stomata that are wider than the central midrib, while the upper surface usually has a few lines of stomata.

The pollen cones grow on the sides of branches, emerging from the bases of the needles. They are about 1 to 2 cm long, although some sources suggest they might be shorter when immature. They are covered in small, resinous protective scales, and the pollen-producing structures are red. The seed cones grow upright on very short stalks. They have a cylindrical shape with a rounded tip and measure between 5.5 and 10 cm long and 3 to 4.5 cm wide. When young, they are pale brown or ochre-colored, maturing to a light brown shade. After the seeds are released, the central cone stalk remains on the tree as a narrow, cone-shaped structure.

The scales that make up the cone are fan-shaped and wider than they are long, typically measuring 1.5 to 2 cm long and 2 to 2.8 cm wide in the middle of the cone. Their surface is smooth but may have fine hairs on the exposed parts. The upper edges are slightly curved backward, while the base narrows into a small stalk. The bracts inside the cone are narrow and spade-shaped, with short, pointed tips, measuring 1 to 1.5 cm long. They remain hidden inside the cone.

The seeds are wedge-shaped, about 7 to 8 mm long, and yellowish-brown. Each seed has a broad, pale yellowish wing that measures 8 to 10 mm long and 6 to 8 mm wide, helping it disperse in the wind.

Subordinate Taxa
There exist 2 subordinate taxa for Abies durangensis:

Distribution

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TDWG Codes
7, 79, MXE, MXE-CU, MXE-DU, MXN, MXN-SI, MXS, MXS-JA

Habitat
The natural habitats for Abies durangensis var. durangensis are temperate forests. It is naturally found at an elevation of at least 3600 up to 3600 metres. Other conifers associated with Abies durangensis var. durangensis are:

USDA Hardiness zone – 8
Abies durangensis var. durangensis is hardy to USDA Zone 8 (Bannister & Neuner, 2001), meaning its frost tolerance lies somewhere in the range of -12.2C (10F) to -6.7C (20F).

Species Continuity
The population trend for Abies durangensis var. durangensis is unknown. There are ongoing threats for Abies durangensis var. durangensis and they are listed as follows:

• 2 Overexploitation & Resource Use
  • 2.1 Logging & Wood Harvesting

IUCN Category – LC
According to the IUCN Red List, Abies durangensis var. durangensis has been assigned the status of LC(Least Concern). This means that according to the Red List criteria, this species is not qualified as threatened.

Superordinate Taxa
The nearest superordinate taxon for Abies durangensis is Sect. Grandis. The coordinate taxa for Abies durangensis are therefore:

Abies durangensis var. durangensis is further placed under Abietoideae. Abies durangensis var. durangensis is also placed under Pinaceae.

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